In recent years, with the progress of high-capacity communication and the like, there has been an increasing demand for optical-fiber connectors as coupling devices for coupling optical fiber cables, in the field of communication and the surrounding fields. Practical examples of the optical-fiber connectors include FC connectors, SC connectors and MU connectors.
These connectors are each provided with a mechanism for avoiding relative turning of optical fiber cables, so as to prevent end portions (contact surfaces) of the coupled optical fiber cables from injuring each other. For example, in the case of the FC connectors, turning in the circumferential direction. is avoided by a, pin and a groove, whereas in the cases of the SC connectors and MU connectors, turning in the circumferential direction is avoided by utilizing the shapes of the connectors. Examples are disclosed in JP-T-2005-533533 and JP-T-2001-507251.
The presence of such a mechanism causes the user to perform positioning in the circumferential direction at the time of coupling the connectors. Particularly, in the case of the connectors of the APC type in which inclination angles are provided at end portions of optical fiber cables in order to suppress reflection noises, positioning with higher accuracy is demanded.
In recent years, in the medical fields also, various medical apparatus have been employed which utilize light such as optical coherent tomography diagnostic apparatus (OCT). These medical apparatus utilize light as a signal, and transmission of the signal is performed by use of an optical fiber cable. Therefore, use of optical-fiber connectors for coupling optical fiber cables is indispensable to these apparatus.
In the medical field, medical personnel oftentimes wear protective garments including rubber gloves. In a situation where the user has to couple a connector while wearing rubber gloves, positioning in the circumferential direction is not easy to perform. Also, when the optical fiber cable is touched by a stained hand, correct transmission of a signal may be difficult, if not impossible. Therefore, it is desirable to preliminarily protect the connector by use of a protective cover or the like, at the time of coupling the connector. In such a case, the positioning in the circumferential direction can become more difficult to perform.